This invention relates generally to a device and method for repairing flanged connections and, more particularly, to a repair device and method for sealing a leak at flanged pipe connections, valve flanges and the like, and also replacing flange bolts in flanged connections, while the pipeline remains in use.
Flanged connections, also known as couplings, are widely used for connecting sections of pipe or ductwork and are often employed for positioning control valves between sections of pipe in a piping network. In many applications, such piping networks serve as conduits for the delivery of fluids under moderate to high pressure. In other applications, such networks operate at pressures lower than the pressure acting upon the exterior of the piping network itself. In either case, the flanged connections are prone to leak. For this reason, among others, various configurations of seals are utilized between the flanges to prevent such leaking. One of the most common configurations includes a raised face on the inner portion of each of the flanges having an annular gasket positioned between the raised faces. When the flanges are bolted together the raised faces compress the gasket material to form a seal.
Leaks often begin in such flange pipe couplings because of deterioration of the gasket material, shifting of the pipe and for other reasons. Similarly, a leak may occur due to defective flange bolts which cause uneven compression on the gasket material. Generally speaking, such leaks must be repaired to prevent damage to the facility housing the piping network, and to maintain proper functioning of the piping system. In the past the pipeline was shut down and drained of its contents before repair could be effected.
Pipe flange repair clamps for sealing the leak between pipe flanges are known in the art. Examples are disclosed in U.S. Pat. Nos. 866,395; 3,152,816; 4,049,296; 4,171,142; 4,230,348; 4,696,453; 4,927,181; and 5,056,830. However, some of the pipe flange repair clamps are extremely complex and have a number of movable and adjustable parts, such as pistons and rings, that make the clamp expensive and difficult to utilize. Moreover, such pipe flange repair clamps normally embody an elastomeric material for centering the clamps around the pipe flanges, and which may provide an initial sealing arrangement between the pipe and clamp. Such elastomeric seals often initially operate properly, but may be adversely affected in certain situations, such as when the leaking fluid is an acid or is at a high temperature and pressure, which can adversely affect the life of the elastomeric material. To solve some of these problems, the elastomeric material can be specially selected, but this still does not solve the compression set properties of the material which often leads to seal failure. Many of the prior art repair devices use sealant injection techniques which can contaminate the process fluid when the injection pressure exceeds the process line pressure.
One aspect of the present invention is directed to a repair device for a flanged connection where the flanged connection is between a first conduit with a first flange and a second conduit with a second flange, the first and second flanges being connected by bolts. The repair device has first and second transfer flanges, each having a first piece and a second piece. The first and second transfer flanges are connected by two or more tension rods and tension nuts. The first and second pieces of each transfer flange are connected by two or more transfer flange joints for reversible attachment around the conduits. The first and second transfer flanges have one or more ram studs removably attached to the transfer flanges between the transfer flanges and flanges. The first and second transfer flanges are axially compressed towards each other along the conduits by applying torque to the tension nuts on the tension rods, thereby axially compressing the first and second flanges on the conduits towards each other by means of the ram studs.
Another aspect of the present invention relates to a repair device including a slide mounting plate positioned removably between the second transfer flange and the second flange on the conduit by means of the tension rods. The slide mounting plate has two or more projections with compression slide tension bolts and has two or more compression slides, each having a first end and a second end. The first end of the compression slide fits between the flanges on the conduits. The second end is in contact with the compression slide tension bolts. The compression slides are radially compressed between the first and second flanges by applying torque to the compression slide tension bolts, thereby radially compressing a sealant between the flanges.
The present invention overcomes a number of the shortcomings associated with other systems and devices now known in the art. The flange connection repair device may be attached to a leaking pipe connection or other flanged connection of an active pipeline and secured thereto. Axial compression may then be applied to each flange of the flanged connection such that each flange is urged toward the other. Torque is transferred from the flange connection bolts to the repair device tension rods. When properly engaged, the repair device ram studs apply sufficient axial compression to the pipe flanges so that one or more of the pipe flange bolts can be replaced without breaking the pipe connection seal between the flanges. When necessary, all of the flange bolts may be removed without breaking the seal, and therefore, without leakage from the flange connection. A sealing material is preferably deposited along the joint of the leaking flange connection and radially compressed by the compression slides such that the sealing material is forced into the joint. Radial compression is preferably applied along the entire circumference of the joint so that the sealing material is prevented from escaping elsewhere along the joint. Applied radial pressure may then direct the sealant into and around the full perimeter of the flange joint while simultaneously applying axial compression with the transfer flanges and ram studs to the flange connection, thereby providing a method for stopping a leak at the flange joint by applying both axial and radial compression.
As will be described in greater detail below, the invention can be used for repairing flange connections of pipe, ductwork, and the like, which operate at moderate to high internal pressures and vacuums. In addition, all repair work may be performed while the piping remains in use.
The present invention provides a number of advantages over other flanged connection repair devices known in the art. For example, the present invention provides a stable platform for maintaining sufficient compression on the flange joint and sealing gasket during removal of defective flange bolts, such that the flange joint maintains a proper seal. As a result, one or more flange bolts can be removed and replaced while fluid continues to flow through the piping being repaired.
Additionally, the flange connection repair device of the present invention is relatively light in weight, portable, and demountable. As a result, the repair device of the present invention can be quickly and efficiently installed onto a flange connection in need of repair, quickly and easily removed following repair, and thereafter transported to additional flange connections in need of repair. Unlike other devices known in the art, the repair device of the present invention need not remain in place on the defective flange connection. Instead, it can be used to facilitate the replacement of worn parts, and can thereafter be removed from the flange connection for reuse as desired.
The present invention further obviates the use of the encasement method of flange connection repair of leaking flange joints. Such methods typically facilitate the pressurization of large quantities of sealant to force sealing material into the flange joint. Such methods are generally difficult to control and often result in sealant unseating the flange gasket, damaging the flange gasket, and/or bypassing the flange gasket and entering the pipe. In such situations, sealant and/or gasket material is inadvertently introduced into the fluid passing through the piping. Such an occurrence generally contaminates the fluid and may necessitate shutting down the lines so that the contaminates can be purged from the system.
Yet another advantage of the present invention relates to the port hole pattern provided in the transfer flanges. The transfer flanges are provided with pass-through port holes positioned such that they may be aligned with the flange connection bolts. As a result, the flange bolts (studs) may be passed through the transfer flanges during replacement of the flange bolts. This facilitates the removal and replacement of flange bolts in those situations where the pipe flange and transfer flange are in close proximity with each other. Moreover, the present invention provides adjustable depth so that the flange connection repair device can be used in low-clearance piping systems.
Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the invention as described herein.
It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide further understanding of the invention, illustrate various embodiments of the invention, and together with the description, serve to explain the principles and operation of the invention.